Wind turbines are renewable energy devices that are being deployed in greater numbers as awareness grows of fossil fuels' disadvantages. The largest percentage of installed cost for wind turbines—certainly for small wind turbines—is attributable to towers and foundations. Development of innovative towers and foundations that have the potential for simplifying turbine installation and reducing cost, will promote more widespread deployment. Of particular interest are free-standing (no guy wires or ancillary supports) monopole towers. They are favored for their visual appeal and maintenance simplicity, but are more costly than guyed towers.
Traditional turbine foundations use a square cross section of the foundation, which is not an efficient shape. While the entire block contributes mass that is useful in resisting the applied overturning moment, the moment arm to the corners can not be assumed because there is no a priori assurance of the loading direction. The corners of the block are essentially wasted space and materials. It would be advantageous to provide a tower foundation created in a shape with no wasted space and materials, resulting in a lower cost.
Another aspect of prior art towers that adds to the cost of installation is having the entire top of the foundation above-ground. This requires extensive forms to create the desired shape and structure, necessitating more materials, design, and labor to install. It would be advantageous to provide a tower foundation which does not require extensive forms to create an above-ground portion.
These towers must have stringently engineered bases able to withstand the forces presented by the turbine and tower. The standard method is to use structurally reinforced concrete. Prior art used grids of rebar manually fastened together, set in concrete, to provide the structure and support. This method is very time consuming and costly. The possibility of error during the fabrication is also significant. It would be advantageous to provide a tower base which does not require tedious, time consuming, and costly assembly with possibility of error.
Prior art tower foundations are generally presented to the customer in the form of plans. The customer then must acquire the materials, cut them, and otherwise prepare them, before assembling the foundation. For people not familiar with the materials, or without the tools to properly manipulate them, this can be a very time-consuming process, with great room for error. It would be advantageous to provide a kit containing all necessary parts for the assembly of a tower foundation.